1. Field of the Invention
The present invention relates generally to devices for dispensing chemicals into swimming pools to maintain the quality and clarity of water therein, and more particularly to a floating dispenser of novel construction for containing solid chemical pellets or tablets therein which are dispensed essentially continuously by nature of dissolution of the solid pellets or tablets by water flowing through the floating dispenser.
Untreated water in both above-ground and below-ground swimming pools tends to deteriorate relatively rapidly due to the growth of bacteria and other organic matter such as algae which result in untreated water quickly becoming both unsanitary and unclear. When the pool water remains untreated for several days, it represents a health hazard to swimmers, and a cleanup problem due to the growth of algae on the surface of the pool.
Water soluble chemicals are added to the pool water to kill the bacteria and to retard the growth of algae. Typically, chlorine is the chemical used to maintain water quality, with the periodic administration of a dose of a liquid solution containing chlorine being the most commonly used treatment. This has some disadvantages, mainly in that a large dosage of chlorine is periodically released as for example in a daily administration of the liquid treatment to the swimming pool. The chlorine level of the water in the pool will therefore vary considerably during the course of even one day, with the chlorine concentration being higher than desirable immediately after the administration of liquid chlorine, and lower than desirable after the chlorine has partially dissipated over a period of time. This diminution of chlorine concentration may vary considerably due to the size and temperature of the pool, the weather, and the amount of use the pool is experiencing as well as other factors.
It is apparent to those knowledgeable in the art that it is instead desirable to maintain the chlorine level at a more or less constant concentration by dispensing the chlorine more frequently, which is impractical in most cases, or by using a specially designed device to dispense the chlorine continuously at a rate designed to maintain a desired concentration in the pool. An early example of such a device is shown in U.S. Pat. No. 3,202,322, to Cleary et al., which teaches a floating dispenser of liquid chemicals which uses a wick to control the rate of propagation of the liquid chemicals into the water of a pool or other body of water. The Cleary et al. device will dispense the liquid into the water continuously, but it is quite difficult to adjust the rate at which the liquid is dispensed. In fact, the removal and replacement of the wick or other components with different sizes of wicks or other components is required to adjust the flow rate of the device.
It is thusly apparent that an important requirement for a chemical dispenser for a swimming pool is its ability to be easily and conveniently adjusted to provide a variable rate of dispersion of the chemicals into the pool to accommodate different pool sizes and other factors influencing the amount of chemicals necessary to be dispensed. A second factor has been found to be the physical nature of the chemical dispensed. While the Cleary et al. device dispenses liquid chemicals, for most people the preferred type of chemicals are the solid chemical pellets or tablets which are more convenient to use than are liquid chemicals.
The chemicals which are currently most widely used in swimming pools for either continuous or daily treatment are the trichloroisocyanurates, which are generally referred to as trichlor. In tablet form trichloroisocyanurates may last as long as one to two weeks, and they leave no residue after dissolving. Although they have the advantage of leaving no residue, they dissolve relatively quickly and therefore only tablets may be used, since pellets would not last for even a week.
Another type of solid pool disinfectant chemical in use is calcium hypochlorite, which is relatively inexpensive and convenient to use. Calcium hypochlorite tablets last for an extended length of time, such as for example two weeks or more in a floating or skimmer feeder. The disadvantage of calcium hypochlorite pellets is that they leave a residue in the floating feeder or on the bottom of the pool after dissolving. Calcium hypochlorite is used mainly for infrequent shock treatments for this reason.
Examples of skimmer feeders are shown in U.S. Pat. Nos. 4,546,503, to Casberg, and in 4,643,881, to Alexander et al. Such feeders are used in forced circulation flow pool systems having a skimmer basket at the location at which water is removed from the pool. The feeder has solid chemical tablets or pellets (referred to hereafter generically as "chlorine tablets") placed inside, and the feeder is placed in the skimmer basket. Chlorine is added to the water as it is drawn out of the pool for filtering and heating. Skimmer feeders are frequently used in large and frequently used pools, such as for example in hotel pools.
Floating feeders are buoyant devices, generally molded of plastic and designed for carrying solid tablets or pellets below the water surface while the device is floating. By either varying the area through which water may flow through the feeder, or by varying the amount of chlorine tablets placed in the feeder, or both, the flow rate of chlorine into the pool water is controlled. The area through which water may flow is usually set by adjusting the area of apertures in the lower sides of the floating feeders. Floating feeders are relatively inexpensive and easy to use, and as such have found particular favor in the home pool market.
Most feeders use a similar type of metering mechanism for selecting the size of the apertures through which water flows into and out of the feeder, and hence the dispersion rate of chlorine into the pool water. This preferred metering mechanism uses a first piece having a plurality of apertures therethrough, which apertures represent the maximum size aperture of the device. A second piece which is typically rotatable with respect to said first piece allows the apertures to be selectively, partially closed to select the amount of water which may flow through the portion of the device containing the chlorine tablets. In this way the dispersion rate of the chlorine into the water may be controlled.
Such floating feeders work reasonably well, but due to their metering design they are susceptible to undesirable changes in the rate of chlorine dispersion due to inadvertent changes in the size of the apertures through which water flows. Such inadvertent changes are usually caused by the feeder being bumped, either by swimmers in the pool or by the feeder being thrown into the edge of the pool by waves in the pool. Upon being bumped the metering mechanism will be unable to resist relative motion between the first and second pieces, causing the size of the apertures to be increased or decreased. It is apparent that it is undesirable to allow such an ordinary and frequently occurring situation to change the rate of chlorine dispersal. Accordingly, it is an objective of the present invention to provide a metering mechanism which will not be changed by bumping of the feeder, however severe.
Another problem with existing floating feeders is that due to the above-described design of the metering mechanism, the rate of dispersion is not precisely setable. This is particularly true with the more inexpensive floating feeders. Often an adjustment of only one-quarter inch is sufficient to move the apertures from fully open to fully closed. This is also unacceptable, and it is a further objective of the present invention that the adjustment of the metering mechanism be easily and conveniently accomplished with a high degree of accuracy.
Another disadvantage encountered in many currently available feeders is caused by the relative rotation between adjacent parts. A device allowing such relative rotation is in most cases secured together by a single rotatable joint such as a screw or rivet, meaning that the feeder is relatively fragile and may be easily broken. This is again one of the main disadvantages of inexpensive feeders. Accordingly, it is a further objective of the present invention for the metering mechanism to be assembled in more secure fashion than by a single rotatable joint.
The aforesaid objectives must be accomplished by a design which both effective and easily and inexpensively manufactured. In the construction of the feeder, it is desirable to avoid all complex forms so as to make the manufacture of the device simple and inexpensive. In addition, the improved metering mechanism must use snap-together assembly. The improved feeder mechanism must also have excellent strength and durability characteristics to ensure a long life.
The resulting feeder metering mechanism must therefore be adjustable over a wide range of dispersion rates, while remaining easy and quick to adjust. It must be completely resistant to changes in the dispersion rate caused by the feeder being bumped. The metering mechanism design must also be inexpensive to implement, while providing greater strength and durability than previous designs. Finaly, the aforesaid advantages and objectives must all be attained while incurring no relative disadvantage.